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Topic: kegging and oxidaiton (Read 1531 times)

New to kegging and Just kegged a pale ale two weeks ago and I getting oxidation off flavors. I transferred from the fermenter to the keg (did not put down a blanket of CO2). Check for leaks, add 5 psi co2 to seal and burp to remove o2, disconnect let sit overnight in fridge, connect set to approx. 12 psi till carbonated. Where in the packaging process could the oxidation happen?

Oxidation can come from excessive splashing from primary into secondary (if you used one), or from splashing into your keg. And purging your keg with CO2 before filling is a good protective step to get in the habit of. Also, it's good to be sure your racking tubing is long enough to reach the bottom of the keg, to minimize the splashing. Did you use a secondary?

EDIT - Also, it looks like you purged the filled keg (which is good), but sealed with only 5 psi, disconnected and left it overnight before reconnecting? If so, that small amount of CO2 was likely not enough to actually seal the keg as some was probably absorbed by the beer, and may have allowed some outside air in past the seal to oxidize. Constant pressure is best. I seat the lid with ~ 30 psi for a minute after purging and then reduce the pressure to my desired carbonation pressure (often 12 psi) and leave it there.

« Last Edit: July 09, 2014, 12:21:13 AM by HoosierBrew »

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Jon H.

S. cerevisiae

I have mentioned this fact more than one time. Cold-side aeration does not lead to the development of 2-nonenal (a.k.a. that stale paper-like flavor). Oxidation that leads to 2-nonenal development occurs during the malting and mashing processes, as 2-nonenal precusors are developed during the malting and mashing processes. In essence, 2-nonenal is a hot-side, not a cold-side phenomenon. Formation of this compound in finished beer occurs in the absence of oxygen.

I have mentioned this fact more than one time. Cold-side aeration does not lead to the development of 2-nonenal (a.k.a. that stale paper-like flavor). Oxidation that leads to 2-nonenal development occurs during the malting and mashing processes, as 2-nonenal precusors are developed during the malting and mashing processes. In essence, 2-nonenal is a hot-side, not a cold-side phenomenon. Formation of this compound in finished beer occurs in the absence of oxygen.

Wow, I had no idea that there were hot-side factors to staling. It has been "accepted knowledge" that oxidation post-fermentation and at packaging is a cause of cardboard off-flavors described as staling. Is this not the case? What can we do to avoid staling on the hot side? And what are the staling effects that we can expect on the cold side?

I have mentioned this fact more than one time. Cold-side aeration does not lead to the development of 2-nonenal (a.k.a. that stale paper-like flavor). Oxidation that leads to 2-nonenal development occurs during the malting and mashing processes, as 2-nonenal precusors are developed during the malting and mashing processes. In essence, 2-nonenal is a hot-side, not a cold-side phenomenon. Formation of this compound in finished beer occurs in the absence of oxygen.

So then, the (only) oxidized batches of beer I have had over the years where I was sloppy in racking, causing noticeable splashing, were all coincidences ? Two of these were hefe/wit styles where, by your info, the copious amounts of yeast in suspension should have easily absorbed the oxidation from splashing and didn't. Sorry, I still don't buy it. I've brewed a long time too, and my only oxidized batches were those where there was a lot of cold side splashing. Not a coincidence.

I have mentioned this fact more than one time. Cold-side aeration does not lead to the development of 2-nonenal (a.k.a. that stale paper-like flavor). Oxidation that leads to 2-nonenal development occurs during the malting and mashing processes, as 2-nonenal precusors are developed during the malting and mashing processes. In essence, 2-nonenal is a hot-side, not a cold-side phenomenon. Formation of this compound in finished beer occurs in the absence of oxygen.

So then, the (only) oxidized batches of beer I have had over the years where I was sloppy in racking, causing noticeable splashing, were all coincidences ? Two of these were hefe/wit styles where, by your info, the copious amounts of yeast in suspension should have easily absorbed the oxidation from splashing and didn't. Sorry, I still don't buy it. I've brewed a long time too, and my only oxidized batches were those where there was a lot of cold side splashing. Not a coincidence.

I think he's referring specifically to trans-2-nonenal, and not all oxidation altogether.

I know I've heard recent interviews with Charlie Bamforth where he has mentioned the same thing - that the cardboard off flavor is formed on the hot side. There is still plenty of oxidation that can happen on the cold side. In those same interviews, Charlie also says that the best things you can do for your beer are to minimize oxygen exposure and store it cold to slow down staling. He's primarily just trying to debunk the old adage that oxidation = cardboard.

I have mentioned this fact more than one time. Cold-side aeration does not lead to the development of 2-nonenal (a.k.a. that stale paper-like flavor). Oxidation that leads to 2-nonenal development occurs during the malting and mashing processes, as 2-nonenal precusors are developed during the malting and mashing processes. In essence, 2-nonenal is a hot-side, not a cold-side phenomenon. Formation of this compound in finished beer occurs in the absence of oxygen.

So then, the (only) oxidized batches of beer I have had over the years where I was sloppy in racking, causing noticeable splashing, were all coincidences ? Two of these were hefe/wit styles where, by your info, the copious amounts of yeast in suspension should have easily absorbed the oxidation from splashing and didn't. Sorry, I still don't buy it. I've brewed a long time too, and my only oxidized batches were those where there was a lot of cold side splashing. Not a coincidence.

I think he's referring specifically to trans-2-nonenal, and not all oxidation altogether.

I know I've heard recent interviews with Charlie Bamforth where he has mentioned the same thing - that the cardboard off flavor is formed on the hot side. There is still plenty of oxidation that can happen on the cold side. In those same interviews, Charlie also says that the best things you can do for your beer are to minimize oxygen exposure and store it cold to slow down staling. He's primarily just trying to debunk the old adage that oxidation = cardboard.

What I'm saying is I had wet, stale cardboard in all those batches, and I find it pretty unlikely that I had HSA and cold side aeration on only those batches. Remember, a couple years ago people were saying that hop stands would run a high risk for high levels of DMS in beer. You and I know it's not so.

He's primarily just trying to debunk the old adage that oxidation = cardboard.

Indeed. Oxidation can take on many, many forms. Almonds, leather, cardboard, honey, catty, aectic, licorice, nutty, 'ball point pen', musty, sherry, etc, etc. Just depends on what the source is and the environment it's in.

Back to the OP, I would look into building a closed transfer set up for transferring your beers from carboy to keg or keg to keg. As has been stated above, minimizing oxygen contact is critical. Reducing temperature swings is another good practice.

S. cerevisiae

What I'm saying is I had wet, stale cardboard in all those batches, and I find it pretty unlikely that I had HSA and cold side aeration on only those batches. Remember, a couple years ago people were saying that hop stands would run a high risk for high levels of DMS in beer. You and I know it's not so.

Notice that I said,"hot-side phenomenon," not "hot-side aeration" in my posting.

Cold-side aeration as a source of 2-nonenal oxidation is a home brewing myth that refuses to die. N. Hashimoto debunked cold-side oxygenation as a source of 2-nonenal oxidation in 1975. A huge amount of research supports Hashimoto's findings.

Charlie Bamforth is indeed a major researcher in this area. He does a lot of work in this area for the large brewers.

He's primarily just trying to debunk the old adage that oxidation = cardboard.

Indeed. Oxidation can take on many, many forms. Almonds, leather, cardboard, honey, catty, aectic, licorice, nutty, 'ball point pen', musty, sherry, etc, etc. Just depends on what the source is and the environment it's in.

I totally agree oxidation can take on many forms, no arguments Amanda. What I was saying, not clearly enough evidently, is that I disagree that wet cardboard-y oxidation smells/aromas can only come from the hot side of the process. I say this because the only 3 times I ever experienced it were after unintentionally splashing my beer into the keg, to a greater extent than I ever had. I changed my racking process (and attention to detail) afterward and never experienced it again.

S. cerevisiae

I totally agree oxidation can take on many forms, no arguments Amanda. What I was saying, not clearly enough evidently, is that I disagree that wet cardboard-y oxidation smells/aromas can only come from the hot side of the process. I say this because the only 3 times I ever experienced it were after unintentionally splashing my beer into the keg, to a greater extent than I ever had. I changed my racking process (and attention to detail) afterward and never experienced it again.

The key phrase in your argument is "attention to detail." Most brewers intentionally or unintentionally change multiple variables when they encounter a brewing problem. The only way to know if a process change results in an improved outcome is to hold everything else the experiment exactly the same. By exactly the same, I mean everything down to the wort composition and the yeast culture.

Forty years of research have proven that lipoxygenase is responsible for the production of 2-nonenal (wet cardboard). Lipoxygenase enzymatically oxidizes linoleic acid to 2-nonenal precursors in the mash. Barley breeders and maltsters are actively engaged in research to limit lipoxygenase in malted barely. Low mash temperature and higher than ideal mash pH activate lipoxygenase. Lipoxygenase is activated at 50C (122F) and denatured at 70C (158F).

As a strategy for inhibiting production of trans-2-nonenal in order to improve flavor stability of malt alcoholic beverages, there"

In closing, I am not saying that cold-side oxidation does not occur, especially after the yeast has been separated from the beer. I am merely bringing to light the fact that cold-side oxidation is not responsible for the development of 2-nonenal. This stale flavor is developed in the mash.

The key phrase in your argument is "attention to detail." Most brewers intentionally or unintentionally change multiple variables when they encounter a brewing problem.

Wrong inference - I lengthened my siphon hose and paid more attention while I racked afterward. No other processes were changed. So by my count, racking is one variable, not multiple ones . Problem went away. Since we clearly disagree (nothing wrong with that whatsoever) I will post no more on this topic. Nothing gained.